Photographic printing with traveling mattes



April 3, 1956 w. E. POHL 2,740,712

PHOTOGRAPHIC PRINTING WITH TRAVELING MATTES Original Filed June 30, 1948 P 1410 mm [90371; 71g; 133% (ER/NT FOREGRoU/vDFba/r/VQ i 2 QUNDEVEL OPED f M2 M5 6, NORMALDE/m/TYFo/PEQRMND ARE/as hDa/az UNEXPOSED BACKGROUND ARE/48 SANDWICH EPR/NrFIRouGH MATTE M314 w a i O/vLow (01v mns r SToc/r ('OMPEA/SA rm United States Patent PHOTOGRAPI-IIC PRINTING WITH TRAVELING MATTES Wadsworth E. Pohl, Los Angeles, Calif., assignor to Technicolor Motion Picture Corporation, Hollywood, Calif., a corporation of Maine Original application June 3!), 1948, Serial No. 36,117, new Patent No. 2,693,126, dated November 2, 1954. Divided and this application June 7, 1954, Serial No. 434,881

3 Claims. (Cl. 95-5) This is a division of my application Serial No. 36,117, filed June 30, 1948, now Patent No. 2,693,126 of November 2, 1954.

In the art of motion picture photography it is desirable to combine two original records such as separately photographed foreground and background action in order to produce on the motion picture screen an image which appears as if the foreground and background scenes had been photographed at the same time, although they have actually been photographed quite independently. This can be accomplished by means of so-called travelling mattes, the foreground action being printed with a background matte which obstructs light from passing through the background areas of the printed film and the background action being printed with a foreground matte which obstructs light from passing through to the foreground areas of the printed film.

Various ways have been proposed to obtain these mattes, many of which include the photographing of the foreground action against a plain, uniform or unpatterned backing. in black and white motion picture photography this backing may be dark or bright. The record of a foreground scene against such a plain and contrasting backing constitutes the starting basis for making silhouette records of background and foreground scenes respectively. Assuming for example that the foreground action has been taken against a black backing, the foreground negalive is used to prepare a matte by making a positive print on high contrast film and developing this film to a high gamma so that the areas of the matte film which correspond to the background are opaque and the areas corresponding to the foreground are transparent. This background matte is then used to print a foreground matte which is opaque in the foreground area and transparent in the background areas so that when superposed over the background film in printing the background the foreground areas are protected and will not print.

In the art of color photography it has been proposed to make travelling mattes by combining negatives made by photographing appropriately colored backings with the foreground action. The color separation records proper can be used for making the mattes, or special matte records may be taken, either simultaneously or alternately with the color aspect records proper. In this field of color photography it has however been found to be exceedingly difficult to obtain adequate separation in the mattes between backing and foreground areas with sharp and sharply registered boundary lines between these areas, mainly because of inadequate saturation of the backing color resulting in inadequate density differences ice which it was made. foreground and background scenes are unsatisfactory because they introduce an unnatural record element which distracts from the enjoyment of the picture.

Various techniques heretofore proposed for improving the above outlined travelling matte technique are very cumbersome particularly for purposes of color photography, and involve a comparatively large number of intermediate records, special cameras and printing methods without actually eliminating the above indicated disadvantages.

Objects of the present invention are to provide a travelling matte technique especially suited for color photography which results in mattes with adequate separation; to provide such a technique which eliminates for all practical purposes matte lines; and to provide a technique reducing the number of films necessary to produce travelling matte pictures, reducing the number of printing and developing steps and producing composite pictures which do not betray the fact that foreground and background actions were exposed separately. Further objects are to provide very intense yet economical illumination for backings used in making matte records; to provide a travelling matte technique for color cinematography employing a considerably reduced number of processing stages and auxiliary records, and employing the emulsions best suitable for picture records without incurring effects detrimental to proper matte matching and the satisfactory reproduction of fine detail in the matte boundaries; and to provide a technique of matte printing which reconciles otherwise contradictory demands of extreme matte opacity, undeviating matte boundary and absence of detrimental flare light effects.

According to the invention, the two areas depicting the background and foreground parts of a picture are printed with travelling mattes by making two mattes both of which are clear in one of the areas and both of which are relatively opaque in the other of the areas, the mattes being made by exposures and developments which are not excessive enough to destroy the fine detail along the boundaries between the areas, and by printing one of the areas from a printing film through both mattes to a film to be printed, the two mattes together furnishing sufiicient masking opacity. If the printing is carried out in projection printing apparatus, one of the mattes can be juxtaposed to one film and the other on the otherfilm, the mattes shielding their juxtaposed films from fiare light.

For the purpose of illustration a typical embodiment of the invention is diagrammatically shown in the accompanying drawings in which- Fig. l is a flow diagram illustrating the interrelation of the various components of the herein described embodiment of the invention; and

Fig. 2 is a diagram illustrating the double matte printing step indicated in Fig. l.

in the particular embodiment of the invention chosen for the purpose of illustration the foreground scene PG is illuminated with white light by a lamp L, against a backing D which may reflect the entire visible spectral range but should at least be fully reflective for green light, and which backing is illuminated as follows. A system of mercury vapor lamps, indicated by lamp BS, is arranged for full illumination of backing screen D through a filter P which is of the yellow appearing blue light absorbing type. As indicated in Fig. 2, mercury vapor lamps have particularly strong emission in two lines in the blue spectral range and in two narrow bands of the green range of the spectrum. As likewise indicated in Fig. 2 a filter (the approximate cut of which is shown at F) eliminates the violet and blue components so that the backing screen D is illuminated only with the strongly Patented Apr. 3, 1956 These matte lines which separate asr enmercury. ines... hree. 910; were. tion negatives are made of a backing D illuminated with mercury vapor lamps filtered in this manner, behind a foreground HG; illuminated with white, light, optimum density difference. between the background: area of the blue: aspect. PNb record (compareFig. l, explained; in detail below) on the; one,hand and the background area of the green aspect record on theother hand is obtained; This density. diiference is at least 1.0-if the negatives are developed to-gamma.0,7, with normal exposure on the foregroundin. both cases.

Theiscene isiphotographed with a light-dividingcarnera of the typedisclosed in. Patent 2,900,058. which comprisesa prism P having an internal light-dividing surface. S, a lens. systemEandtwo filrngates. Through one film gate passes. a greensensiti-ve filmQENg, and. through the other film. gatepasses a bipack comprising films Phil; and EN:- to record the blue and red aspects respectively. The green aspect film, FNg. is, exposed through a greenfilter G and, iii film FNr is effectively green sensitive, the other two films are exposed through a minus green filter MG. According to common practice. one of films FNb and EN? of the bipack carries. filtering material to prevent blue light reaching the red aspect negative FNr. it will be noted that the above mentioned patent shows the.

bipack in the reflected beam,.wherea s Fig. 1 shows it in the direct beam, a likewise; feasible arrangement.

The blue, green and red aspectsof the foreground scene are thus photographed" and. the latent records then developed to normal contrast. on. the three films as illustrated, in Fig. 1. Inasmuch as thefilter MG absorbs the green light from the backingand the combination of lamp BG and lamp filter F excludes from the backing any light to which film FNb is sensitive, the, background area of this film FNb remains unexposed.

Due to intense illumination of the white backing with light to which film FNg is particularly sensitive the green aspect negative FNg is heavily overexposed in the background area. Pig. 1 illustrates the lack of exposure of the background. area of film FNb and the intense ex-. posure of the corresponding area of FNg. Since film FNiis little green sensitive or green light is excluded therefrom by filter N6, the background area of FNr remains unexposed, as: illustrated in Fig. 1.

From the three foregroundnegatives FNb, FNg and FNr, three positives; namely foreground masters FMb, FMg, and PM! are printed asillustrated in Fig. 1.

From the green aspect negative FNg a foreground positive F Pg is' printed and developed in the usual way.

Owing to the heavy density of the background area of the negative this positive is" clear in the background area, as indicated in Fig. 1. I

Withthe blue aspect negative FNb of the foreground and the green aspect positive FPg' of the foreground in superposition, three mattes M1, M2 and M3 are printed as illustrated in Fig. 1.

Inasmuch as the two printing-films FNb and FPg are clear in the background areas the mattes can be heavily overexposed in these background areas without substantial exposure in the foreground areas. The two mattes M1 and M2 are printed on high contrast stock of the type usually employed for work ofthis type, for example film sold under the trade designation Eastman Matte Stock 1363 which is ordinarily processed to a gamma of 3.0 or greater. These films are: developed to background, area densities which are approximately normal for this type of emulsion such as about 1.5 but which, added together, total approximately 3.01 to 4.0. v

The matte M3 is, in accordance with the invention, printed. on low contrast stock such ascustomarily used in printing master positives, for. example Eastman yellow-dyed Master'Stock 23 65 whichnormally develops to a gamma of.1.2' to. 1.6; In accordancewith the invention. this film M3 is; developed to a density in theneighborhood of 3.0. It is understood that the above densities are merely illustrative as to general order of magnitude but not critical.

The use of low contrast stock in making the matte M3 is contrary to the usual practice of making matte films, it being customary to use high contrast stock for that purpose, such, stock being also used in the present example for mattes M1 and M2. The reason for the use of low contrast stock for matte M3 is the discovery that. with such stock the developed silver along the borderline between the heavily overexposed background area and the unexposed foreground area grows into the foreground area, thereby enlarging the size of the background area and'correspoudingly reducing the size of the foreground area. By purposely inducing such growth in the manufacture of this matte, an opposite growth in a later stage of the process, unavoidable if picture records of good quality are desired, is counteracted as hereinafter described.

The blue, green and red aspect negativesof the background BNb, BNg and BNr in Fig. 1, may be made in any suitable. way as for example by means of a camera such as illustrated in Fig. 1. From these negatives blue,v green and red master positives BMb', 'BMg and BMr are. printed. Each of these three positive films is then reprinted upon by exposing it prior to development through the matte M3 to form on low contrast stock the. background masters BMb, BMg and BMr respectively as shown in Fig. 1. Inasmuch as the master positives BMb, BMg and BM) are heavily overexposed in the fore ground area andv since they are on low contraststojck, the silver along the border line of the exposed area tends to grow into the g ackground area as above described'with. reference to matte M3. This growth counteracts the growth involved in the manufacture of the matte M3] as illustrated in Fig. 1. If the respective growths are prop erly controlled, the opaque foreground areas of the mas ter positives correspond in size to the foreground scene.

While th e correlation of two matte systems such as M3 and masters BM. by way of record growth in opposite sense may be fairly accurate without special control of this phase of the process so long as similar stock is used for both prints, it is particularly reliable if the record growth is controlled and correlated with the original optical image and a matte or mattes of the conventional type, in the manner described in my above mentioned copending applicationSerial No. 36,117.

From the three'foreground masters FMb, FMg and FMr (Fig. l) the masked records CDb, CDg and CDr are printed through matters M1 and M2 as illustrated in Figfhthereby to produce latent records having normal density in the foreground areas and being unexposed'in the background areas. The matte M2 is superposed over eachmaste r' and the matter M1 is superposed over each masked record film, in' sandwich form, during each'of the three copying steps in a projection printer. The films CDb, CDg, and CD are then exposed again to the background masters BMb, BMg and BMr to produce the final composite records CD17, CDg and CDr as illustrated in Fig. 1. These records may then be employed in any color process, as for example an imbibition process.

By employing two mattes M1 and M2 in printing the composite records as illustrated in Figs. 1 and 2 several advantages are obtained. In the first place heavy overexposure or heavy overdevelopment in making the mattes is unnecessary. On the contrary they may be printed lightly enough so that fine detail is not lost along theboundarybetween the foreground and background areas. When usinga single matte which is necessarily heavily overexposed or overdeveloped, or both, much of this dotail is lost; Forexample in the case of wisps of hair around a womans head, the fine hairlines extending out into the gackground area are largely or entirely lost in the usual methods involving a single matte. However with the-present invention these stray wisps of hair print naturally even though surrounded by background scenery.

The two masks, each of fairly normal density but as pointed out above together of a density about 3.0 nevertheless furnish proper high density if used in superposition. In addition to the beneficial effects of providing high density and preserving fine detail, the use of two masks further provides the possibility of preventing or at least diminishing the elfect of flare while printing records CD from masters PM. By using one matte in contact with a foreground master PM and the other in contact with the film CD, in the projection printing illustrated in Fig. 1, one matte prevents flare light from the background areas of the masters from afiecting the foreground areas of the composite dupes, and the other matte which is used in the contact head prevents flare light from the foreground areas affecting the background areas as indicated in Pig. 2. In this figure Ep is the lens system of a projection printer. The arrangement of records FM, masks M1 and M2 and of stock CD will now be evident in view of the above description referring to Fig. 1. The full line ray 7' indicates the actual printing beam, whereas the dotted ray rf indicates the flare light which would impinge on the supposedly unexposed portion of CD if masks M1 were not present, whereas dotted ray rg indicates the flare light which would impinge on the record portion of CD it mask M2 were not present.

it should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim:

1. In the art of separately printing with travelling mattes the two areas depicting the background and foreground parts of the pictures respectively, the method which comprises making two mattes both of which are clear in one of said areas and both of which are essentially without internal detail and less than completely opaque in the other of said areas, by exposures and developments which are not excessive enough to destroy the fine detail along the boundaries between said areas, and printing one of said areas from a printing film representing a respective one of said parts through both mattes to a film to be printed, the two mattes together furnishing sufiicient masking opacity.

2. In the art of separately printing from film records with traveling mattes the two areas depicting the background and foreground parts of pictures respectively, the method which comprises making two mattes both of which are clear in the same one of said areas and both of which are relatively opaque in the other of said areas, the mattes being made by exposures and developments to densities the sum of which is in the region of 3.0 so as not to destroy the fine detail along the boundaries between said areas, and printing one of said areas by projecting light from one of said film records through both mattes to a film to be printed, one of said mattes being juxtaposed to one film and the other matte juxtaposed to the other film, the two mattes together furnishing sufficient masking opacity and each shielding its juxtaposed film frorn flare light.

3. In the art of separately printing from film records with travelling mattes the two areas depicting the background and foreground parts of pictures respectively, the method which comprises making two mattes both of which are clear in one of said areas and both of which are relatively opaque in the other of said areas, the mattes being made by exposures and developments which are not excessive enough to destroy the fine detail along the boundaries between said areas, and printing one of said areas by projecting light from one of said film records through both mattes to a film to be printed, one of said mattes being juxtaposed to one film and the other matte juxtaposed to the other film, the two mattes together furnishing suflicient masking opacity and each shielding its juxtaposed film from flare light.

References Cited in the file of this patent UNITED STATES PATENTS 1,468,965 Hall Sept. 25, 1923 1,670,195 Gerland May 15, 1928 1,960,373 Dreyer May 29, 1934 2,396,726 Trimble Mar. 19, 1946 

1. IN THE ART OF SEPARATELY PRINGING WITH TRAVELLING MATTERS THE TWO AREAS DEPICTING THE BACKGROUND AND FOREGROUND PARTS OF THE PICTURES RESPECTIVELY, THE METHOD WHICH COMPRISES MAKING TWO MATTES BOTH OF WHICH ARE CLEAR IN ONE OF SAID AREAS AND BOTH OF WHICH ARE ESSENTIALLY WITHOUT INTERNAL DETAIL AND LESS THAN COMPLETELY OPAQUE IN THE OTHER OF SAID AREAS, BY EXPOSURES AND DEVELOPMENTS WHICH ARE NOT EXCESSIVE ENOUGH TO DESTROY THE FINE DETAIL ALONG THE BOUNDARIES BETWEEN SAID AREAS, AND PRINTING ONE OF SAID AREAS FROM A PRINTING FILM REPRESENTING A RESPECTIVE ONE OF SAID PARTS THROUGH BOTH 